From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Design drawing of an expansible track friction drive mechanism.
| Identifier | ExFiles\Box 136\4\ scan0023 | |
| Date | 7th October 1925 guessed | |
| A Crankshaft + driving shaft B Friction wheel + driven member C Expansible track. Aug II. | ||